When a vehicle with a low ride height (hereinafter referred to as a small vehicle) such as a passenger car collides head-on with or rear-ends a vehicle with a high ride height (hereinafter referred to as a large-sized vehicle) such as a truck, the small vehicle may go under the bottom of the large-sized vehicle. In order to prevent such an inconvenience, it has been known that the large-sized vehicle has an underrun protector provided at its front or rear.
Patent Document 1: Japanese Patent Application Publication No. Hei